According to the method described in German Published Patent Application No. 100 43 499, at least one data record, which may be, for example, program code or information stored in a memory of a processor unit for further use and then used in the course of a program, is transmitted to a processor unit such as a control unit of a motor vehicle. The at least one data record is transmitted together with additional information, for example as a cohesive data packet, from the data source to the processor unit. The processor unit loads the transmitted data into a buffer memory belonging to it. The processor unit then establishes contact with an external checking unit, in particular by remote data transmission, identifies itself with the external checking unit and transmits to the latter at least a portion of the additional information. On the basis of the transmitted portion of the additional information and the identity of the processor unit, the external checking unit verifies whether or not the use of the at least one data record in the processor unit is allowed. Depending on the result of this check, the processor unit transmits either an enable signal or a blocking signal. In the case when the blocking signal is transmitted, the at least one data record is deleted from the buffer memory. Otherwise the at least one data record thus transmitted is used in the processor unit.
It is desirable if the data records stored in processor units such as the control units in motor vehicles are modifiable externally. This may be accomplished, for example, for the purpose of updating such control units without having to replace the control unit. Data records may be transmitted to the control unit via remote data transmission or via a suitable interface connected to the processor unit such as a diagnostic interface of a motor vehicle. The data records are provided on a data source, which may be data memories or data processing devices.
It is first important to ensure that only authorized data records are transmitted to and used by the processor unit. Any unallowed change in the data records or input of data records that have not been enabled should be prevented because using non-enabled data records may cause problems in operation of the processor unit or other processor units connected to that processor unit. Furthermore, the upload procedure should be as simple as possible.